1. Field of the Invention
This invention relates, in general, to automatic switches and, more specifically, to appliance timers such as those suitable for electric ranges.
2. Description of the Prior Art
Timers are used frequently on major appliances to control their starting time and the duration of their operation. When used with ranges and ovens, such timers usually automatically control the time at which cooking begins and stops. Such timers must be reliable commensurate with a reasonable cost of manufacturing such items. U.S. Pat. Nos. 3,038,041, 3,440,370, 3,686,450, and 3,712,966 disclose timers which are of the type suitable for automatically controlling an electric range.
Many applicance timers have at least two shafts which may be moved to set the starting and stopping times for automatic operation. In one such prior art arrangement, the shafts move a rocking lever which in turn opens and closes the electrical contacts of the timer. One shaft is used to place the timer in a manual position for nonautomatic operation of the appliance. When in the manual position, one end of the rocking lever is held in a raised position to maintain closure of the switch contacts. The rocking lever is held in this position by a locking lever which holds one of the shafts in a raised or inward position against the rocking lever. Thus, according to this prior art arrangement, one shaft must be maintained in a particular position to permit manual operation of the associated appliance.
When using one of the shafts to hold the rocking lever as taught by the prior art, the position of the shaft becomes critical. The shaft which sets the switch for manual control must be held inward to hold the rocking lever in the desired position. Due to the construction of this type of timer, the indicating pointer attached to this shaft will not point to the correct time since it cannot be rotated by a motor-driven gear mechanism when in the inward position. Consequently, confusion and misinterpretation of the time settings is possible. Therefore, it is desirable, and it is an object of this invention, to provide an appliance timer in which both the starting and stopping shafts can rotate automatically according to the correct time when the timer is set for manual operation.